Assxgkmoj to american telephone



Oct. 9 1923.

H. A. AFFEL CARRIER TRANSMISSION ROUTING ARRANGEMENT Filed July 24',1919 2 Sheets-Sheet 1 INVENTOR ATTORNEY Oct; .9 1923.

H. A. AFFEL CARRIER TRANSMISSION ROUTING ARRANGEMENT Filed July 24, 19192 Sheets-Sheet 2 INVENTOR BY W ATTORNEY Patented Oct. 9,

UNITED-sures HERMAN A. AFEEL, OF BE JGOKLYN, NE'W YORK, ASSIGNOR TOAIVEERICAN TELEPHONE PATENT orF cE;

AND TELEGRAPH COIVIP ILNY, A CORPGR-A'IION [0F NEW YORK.

onnmnn-rnnnsraissronneuritis nnnimenrrnn'r.

Application filedJuly 24,

To all whom it may concern:

Be it known that I, HERMAN A. Armin,

residing at Brooklyn, in the county of Kings and State of New York, haveinvented certain Improvements in Carrier-Transmission- RoutingArrangements, of which thefOlIOW- in;- is a specification.

This invention relates to multiplex transmission andin particular tomultiplex systems in which carrier currents are employed for thetransmission of signals. 7

It has been proposed to multiplex an ordinary wire transmission linesuch as a telephone or telegraph line by superimposing thereon aplurality of carrier currents of different frequencies, said carriercurrents being used for the selective transmission oi telephone ortelegraph signals. -While a sy tom of this character presents thepossibility of impressing upon a common wire circuit a. number ofadditional channels OfCOiDIIlH- nication by the provision of certainterminal carrier apparatus, it has inherent disadvantape that if anydefect should occur upon the common transmission line, such a break, across, or a ground, such detect will. result in putting out ofcommission a large number of circuits instead of a single circuit.

In accordance with the present invention it is proposed to overcome thisdifiicul'ty by providing one or more alternative low irequencytransmission lines whi h are not normally used for carrier transmissionso that in the case of trouble occurring upon any line normally used forcarrier transm s-' sion the terminal carrier apparatus may bedisconnected from the line'upon which the trouble has occurred andconnected to one or the alternative lines so that carrier trans missionmay take place thereover. r

In order to simplify theoneration of shifting the carrier channels fromawline to arrange the connection so that the switch mg operations mayperformed by a simple switching means such as a plug and stations and Bto jacks eel-m nd. 3134311 without disarran gingzthe -wiring at theterminal station where the carrier apparatus is located.

- Since the wire transmission lines which extend between two points overwhich carrier transmission is to take place may in some instances betwo-wire circuits and in other instances four-wire circuits, it is alsoproposed, in accordance with'the present invention, to provide suitableswitching means associated with the terminal carrier apparatus wherebysuch apparatus may be arranged to operate either on a two-wire or afoiirivire basis. Bythe provision of these switching arrangements thesame terminal carrier apparatus may beoperatedon a twowire basis wherethe carrier transmission is normally routed over a two-wire line and maybe operated upon afour-Wirebasis when in case of a trouble on thetwo-wire line it is necessary to shift the connections of the terminalapparatus to an alternative understood by reference to the following,

description when read in connection with the accompanying drawings,Flgure l of which discloses a circuit arrangement of one modification ofthe invention; Fig. of which constitutes a circuit diagram embodyingtwoadditional modifications of the in vention and Fig. 3 of which is adiagrammatic showing of certain details of the terminal carrierapparatus pertaining to a sinszle transmission channel.

Referring to Fig. 1, ML represents a telephone transmission line of theusual charr cter terminatingat stations A and B in the usual compositesets GK and CXt of well- .l'rnown construction whereby the line is com-.posited for transmitting telegraph signals in addition to telephonicsignals. In order that the line may be utilized for carriertransmission, branch connections are extended at the and Tel resectively, these jacks co-operating with the plugs P and? of terminalcarrier apparatus. Low pass filters LFandLFf are provided at stations Aand B for preventing zeorge the transmission of carrier oscillations tothe terminal telephone circuits LT and LT. These filters are broad bandfilters of the eneral type disclosed in U. S. patents to Campbell Nos.1,227,113 and 1,227,114, dated May '22, 1917. The filters are soproportioned as to transmit frequencies ranging from zero to the upperlimit of frequencies employed in ordinary telephonic transmission whilesubstantially suppressing frequencies above this limit.

, The terminal, carrierapparatus at station A includes a carrier branchCB terminating in the plug P adapted to cooperate with the jack LJ saidcarrier branch including a high pass filter HF. The filter HF is also ofthe general type disclosed in the patents .to Campbell above mentionedand is so de signed asto transmit a band of frequencies extending abovethe upper limit of frequencies employed in ordinary telephonic transmission while substantially suppressing frequencies below this limit.The carrier branch CB is associated through a balanced transformerarrangement 10 with a common transmitting circuit TL and a commonreceiving circuit RL. A gbalancing network MN is provided to balance theline ML and associated apparatus at the station A so that the circuitsTL and RL are rendered conjugate with respect to each other; that is,

disturbances arising in the one circuit will not affect the other. Aplurality of low frequency transmission lines L and L etc. are connectedto carrier translating arrangements C C etc, said translatingarrangements terminating in transmitting channels TL TL. etc. andreceiving channels RL R11 etc, the several transmitting channels andseveral receiving channels being connected to the common transmittingandreceiving circuits TL and RL, respectively.

The function of the carrier translating apparatus is to translate thelow frequency signals incoming from the low fre uency lines intohiglrfrequency carrier oscil ations of the frequency assigned to thatparticular channel'for transmission purposes, and to translate highfrequency carrier oscillations of the frequency assigned to theparticular channel into low frequency signals for transmission over thelow frequency lines as well as to provide meansfor separating thesevw-rral carrier frequencies into their proper' -VVh1le the details ofthe carrier hannels. translating apparatus form no part of the presentinvention, a general idea of this apparatus may be had by referring'toFig; 3

which illustrates in simplified form the cir cuit arrangements of thetranslating apparatus C 5 It willbe ui'idcrstood of course that thetranslating apparatus of other channels will'be similar. Y

Referring to Fig. 3 the line L is associated through a balancedtransformer arrangement 11 and a balancing network N with transmittingand receiving channels TL and RL The transmitting channel includes aduplex vacuum tube modulator M arranged to normally suppress the carrierfrequency supplied thereto 'over the circuit 20 and to transmitoscillations of the frequency supplied over the circuit 20 mochr.

cies ordinarily employed in telephonic trans mission. The modulatedcarrier oscillations transmitted through this filter are amplified bythe duplex amplifier TA of well-known construction and are thentransmitted through a second filter TF similar to the filter TF and overthe terminal portion of the transmitting channel TL to the commontransmitting circuit TL of Fig. 1.

The receiving channel RL of Fig. 3 includes a filter RF similar tofilters TF and 'Tlif already described. A duplex vacuum tubedetectoroperatingon the Well-known homodyne principle and supplied overthe circuit 21 with homodyne oscillations of the ciated with thereceiving circuit RL and operates to detect or translate the modulatedthence to the line L The filter R11 is a low frequency filter similar inconstruction to the filter LF already described.

The terminal carrier apparatus at the station B is similar to thatalready described at station A and COIHPIISQS a plug P adapted tocooperate with the jack LJ, a high frequency filter HF; carrier branchCB,

transformer 10 artificial line MN, common frequency assigned to thechannel is assotransmitting circuit TL, common receiving circuit RL andcarrier translating arrange ments C and C associated with the lowfrequency lines L and L By inserting the plug P in the jack LJ and theplug P iii-the jack LJ, carrier transmission may take place betweenlines L and L between lines L and L etc. over the line ML in addition tothe low frequency transmission taking place between the terminalcircuits LT and LT. Should any trouble, however, occur upon .everthccontacts of and terminating in low frequency telephone circuits L T andL T'. In order that this line may be used for carrier transmission whendesired, low. ass filters L F and L 1 similar to filters F and Ll areinserted inthe terminal circuits, and branch connections are providedleading to jacks LJ and L J adapt-ed for cooperation with the plugs Pand P of the "terminal carrier apparatus. As soon as any trouble occurson 'theline ML the plugs l and P may be withdrawn from the jacks LJ andLil and inserted in the jacks LJ and L J of the alternative line M L sothat the carrier transmission may instead of the line ML.

It will be noted that in making this change no substantial alteratiouofthe alternative or reserve line M L is ne ;essary, since the carrierapparatus is all self-contained and the high frequencyfilters areincluded in the carrier circuit. 5 It is only necessary to provide thelow frequency filters L F and L F in the main line M L and even thesefilters would normally be present it repeater points occurred atstations A and B although the line M L were only used for low frequencytransmission, it being desirable to provide these filters in order toprevent high frequency disturbances due to external causes from beingtransmitted to the repeaters. g

tis possible, however, to arrange the circuits so that even the low passfilters, such as LF may be included in the terminal carrier apparatuswith the consequent result that no modification of the ordinarytransmission line used as an alternative or reserve route is necessary.An arrangement embodying this additional feature is illustrated in Fig.2 in which the terminal carrier apparatus at the station Ais for themost part Ede 'cal with that illustrated in Fig. 1, like characters. Theterminal carrier apparatus modified, however, to the extent that itninates in two plugs and 23 instead at single plug P, the low passfilter Ll? being included in a branch connection exir m the carrierbranch Cll to the plug-522. The main line ML extends.

ts 26 and 2 '7 and rough the composite set to the termin..l'circu1t' LT.Bv'mscrting the plugs 22 V andZSin the jacksQG and the direct coniectionbetween the main line ML and the now take place over the line M L i wireline or a tour-wire line.

being identified by the same rete ace.

7 ,etc. associated with transmission lines and so that the plugs 22 andmay h 'withdrawn from jacks 26 and 2'? a d in serted in jacks 242 and25, thereby inserting the low pass filter LF between the main line M Land the terminal. circuit Lfl, the carrier apparatus being newassociated the main line ll'l L through the carr er branch CB.

- \Vhile in practice the terminal apparatus at stations A. and B mightbe identical, for purposes of illustration, a modified terminalarrangement is shown at station B, the agparat-us illustrated at saidstation being designed so that the terminal carrier apparatus may beassociated with either a two- In this case the main line ll L isconnected at station B through the filter LF to terminal circuit LT anda branch including a high. pass filter HF terminating in a jack 32isprovided for connecting the terminal carrier apparatus to the mainline. A second jack connected to an artificial line MN for balancing themain line ML and its associated apparatus is also provided. Jacks 3'12and 33 are adapted for cooperation with plugs 28 and 29 associated withthe terminal carrier apparatus.

As an alternative route for carrier transmission the line M,L is shownas a two-wire line extending from station A to a point intermediatestations A; and B, where it is converted to a four-wire circuitincluding transmission lines LE and LWV through the medium oftransformer 34 and balancing artificial line M N. Repeaters RE and RVVmay be includedL in the lines LE and LlV in a well-known manner. Thetwo-wire lines LE and LW which comprise the four-Wire 81 are adaptedtocooperate with the plugs and 29 of the terminal carrier apparatusalready referred to.

. The terminal carrier ap carrier translating arrang L etc., similar tothe corresponding apparatus at station ..i. The carrier apparatus alsoin:.:i.udes a common transmitting circuit TL associated through theiiulividualv transnutting circuits TL .TL etc, with the translatingapparatus C,',"C etc. A comzuit TL is connected over the contacts of ack35, over conductors 3G and contacts of jack 3:7 to the plug 28. Thecommon rerowing circuit 1th is ronnected over the "ontacts of jacl: 38,transformer 39, conductors 40, contacts oi. acl: 41 and over conductors42 to the ack 29. Vith the circuits oi? the earrier terminal apparatusin the condition just described said. apparatus is adapted to operate onthe four-wire basis and by inserting the plugs 28 and 29 injacks and 31,carrier transmission may take place over the two-wire line ML and thetourwire line LEL\V. It will be under stood, of course, that the carrierapparatus at station A will be associated with the line ALL by insertingthe plugs 21 and 23 into the jacks 24 and 25.

Carrier transmission from the carrier apparatus at station A passes overthe main line M L, through the transitormer 34, repeater RE, over theline LE, through the high pass filter HFV, over the contacts of jack 31and plug 29, over the circuit 42, contacts of ack 41, over circuit 40,through transformer 39, over the contacts of jack 38 into the commonreceiving circuit RL, trom C etc. and combined in the common trans--quitting circuit TL From this circuit transuussion takes place over thecontacts of jack 35, over conductors 36, contacts of jack 37, contactsof plug 28 and jack 30, through the high pass filter HFE, over the linLWV through the repeater RW and over the line M,L into the carrierbranch CB and thence to the carrier apparatus at station A.

Should it be desired to associate the carrier apparatus with the line MLthe plugs 28 and 29 will be inserted in the jacks 32 and. 33,respectively. The terminal. carrier appaa ratus must now be arranged tooperate on a two-wire basis. For this purpose, in addition to the jacksalready described, jacks 48, 4-4, 4.5 and 46 are n'ovided. Four patchingcords terminating in plugs 4:74:8,

Lil-50, 5152 and 53-54 are now inserted in the pairs of jacks 3543,38-44:, 4;1.4 -5 and 4637, respectively;

Carrier transmission from station A now passes over the main line ML,through filter HE, over the contacts of jack 32 and plug contacts ofjack 3?. and plug 54-, contacts of plug 53 and 'jacl: 46, through thetr: .isformer 55, over conductor 56, con

tacts of jack L3 and plug 48, contacts of plus: 4:1 and pick 35 to thecommon transmitting circuit TL and thence through the carriertranslating apparatusto the individual low frequency lines. Incomingtransmissions from the low frequency lines attcr being translated intomodulated car riier frequencies are combined in the common receivingcircuit RL and-pass over the contacts o't jack 3S andplug 4.9, contactsor plug and jack 4%, through the balanced traustormer 57 where theenergy divides, part lowing-over coiuluctms58, contactso'f.

jack to and plug 53, contacts ofplug' 54: and 136k -57 and over thecontacts of plug 28 and act: 32, through the high frequency lilter F tothe main line ML. The other ergy is diverted through the transformer 55into the transmitting circuit TLC It will be noted that the balancedtransformer arrangement 57 is included in the terminal carrier circuitwhen the carrier apparatus is to be'operated on a two-wire basis, saidtransformer arrangement performing substantially the same functions as,that per formed; by the transformer 34 of the fourwire circuit when thecarrier apparatus is operated on a tour-wire basis. The essential:t'unct'ions performed by the four patching cords and their associatedjacks consist in connecting 0r disconnecting the balanced transformerarrangement 57, depending on whether the operation is to be on atwo-wire or four-wire basis.

It will be understood, of course, that either the line ML or the line ML and the fourwire circuit may constitute the normal route for carrier tansmission, the other route being an alternative route to be utilizedwhen for any reason the normal route is out of commission. It will alsobe understood that where the fourwire circuit extends to bothv carrierterminals the apparatus at both stations A and B may be similar to thatat station B.

The invention above described providesa relatively simple and eiiicientsolution for the diiticulties arising: from the factthat troubleoccurring on a line used for carrier transmission results ina largenumberof circuits going out 01f service. Furthermore, the apparatusnecessary for overcoming the difficulties herein sought to be eliminatedis associated either wholly or in part with the I terminal carrierapparatus, thereby involviiig little or no change in the low frequencycircuits. v

It will of course be obvious that the general principles hereindisclosed may be em-i Air 'minalcarrier an oaratuswith'an one of saidtransmission lines s'o'that carrier oscillations may be transmittedthereover.

2v In signaling system, fa plurality of transmission .linesladapted totransmit low frequency sigiialingcurrents and high fre quencyoscillations of the order employed for carrier transmission, terminalcarrier ap- 1 ratus including means for translating a urality of highfrequency carrier oscilla- JOBS into independent low frequency signalingcurrents, and switching means for as seciating said terminal carrierapparatus with any one of said transmission lines so hat carrieroscillations maybe transmitted hereover. i

In a signaling system a plurality of transmission lines adapted totransmit low frequency signaling currents and high frequencyoscillations of the order employed for carrier transmission,terminalcarrier apparatus including means for translating a plurality ofindependent low frequency signaling currents into high frequency carrieroscillations of difierent frequencies and means for substantiallypreventing the transmission of low frequency signaling currents .to saidcarrier apparatus, and switching means for associating-said terminalcarrier apparatus with any one of said transmission lines so thatcarrier oscillations maybe transmitted thereover and low frequencysignaling'currents will not be transmitted to said terminal carrierapparatus from said transmissionlines.

4. In a signaling system, a plurality of transmission lines adapted totransmit low frequency signaling currents and high frequencyoscillations of the order employed for carrier transmission, terminalcarrier apparatus including means for translating a plurality of highfrequency carrier oscillai tions into independent low frequencysignaling currents and means for substantially preventing thetransmission of low frequency signaling currents to said carrierapparatus, and switching means for associatin said terminal carrierapparatus with any one of said transmission lines so that carrieroscillations may be transmitted over said lines to said terminal carrierapparatus while low frequency signaling currents will not be transmittedto said apparatus from said transmission lines. I a I 5. In a signalingsystem a plurality of transmission lines adapted for the transmission oflow frequency signaling currents and high frequency oscillations of theorder employed for carrier transmission, low frequency terminal circuitsassociated with each of said transmission lines to transmit lowfrequency signals directly thereto, terminal carrier apparatus includingmeans for translating a plurality of independent lowfrequency signalingcurrents into high frequency carrieroscillations of differentfrequencies and means for substantially preventing the transmission oflow frequency signalin currents to said terminal carrier apparatus, andswitcning means for associating said teriniinal, carrier apparatus withany one of said transmission lines, said switching means hayingassociatedtherewith means for substantially preventing the transmissionof carrier frequency signaling currents and operating when associatedwith a given transmission line to establish such connections between thetransmission line, a terminal circuit and said last mentioned means thathigh frequency oscillations transmitted over said line will betransmitted to said terminal carrier apparatus without substantialdiversion to tie low frequency terminal circuit associated with saidline, and low frequency signaling currents will be transmitted oversaidline to said low frequency terminal circuit without beingsubstantially diverted to said. terminal carrier apparatus.

6. In a signaling system, a plurality of transmission lines adapted forthe transmission of low frequency signaling currents and high frequencyoscillations of the order employed for carrier transmission, lowfrequency termi l circuits associated with each of said transmissionlines to transmit low frequency signals directly thereto, terminalcarrier apparatus including means for translating a plurality of highfrequency carrier oscillations into independent low frequency signalingcurrents and means for substantially preventing; the transmission of lowfrequency signal ng currents to said terminal carrier apparatus, andswitching means for associating said terminal carrier apparatus with anyone of said transmission lines said switching means having associatedtherewith means for substantially preventing the transmission of carrierfrequency signaling currents and operating when associated with a giventransmission line t establish such connections between the transmissionline, a terminal circuit and said last mentioned means that high"frequency oscillations transmitted over said line will be transmittedto said terminal carrier apl'iaratus without substantial diversion tothe low frequency terminal circuit associated with said line, and lowfrequency signaling currents will be trans- 'tarrier apparatus adaptedto operate either on a two-wire or a four-wire basis for the two waytransmission of carrier frequencies, switching means to associate saidcarrier apparatus with either of said transmission lines, and switchingmeans associated with said carrier apparatus whereby the circuitsthereof may be adapted for two-wire operations when associated with thetwo-wire transmission-lines, and may be adapted for tour-wire operationswhen associated with the four-wire line. a

8. In a signaling system, a two-wire transmission line and a four-wiretransmission liney both lines being adapted to transmit low frequencysignaling currents and high frequency oscillations 0i the order employedfor carrier transmission, terminal carrier apparatus for the two waytransmission of carrier frequencies, said carrier apparatus including aplurality of carrier channels associated with a common carrier circuit,switching means associated with said common carrier circuit whereby saidcarrier apparatus may be associated with either of said transmissionlines, and switching means whereby when said carrier apparatus isassociated with said two-wire transmission lines said'common carriercircuit will be connected for two-wire tlfiIlSI'DlSSlOIl and whenassociated with said tour-wire'transmission lines said common circuitmay be translated into a four-wire terminal circult.

In testimony whereof, :I have signed my name to this specification this23rd day

